In the Sky This Month

The Moon is at the eastern edge of Aquarius tonight, quite near Trappist-1, a star that hosts seven known planets, more than any system other than our own. The star is tiny and feeble, though, so it’s too faint to see with the eye alone.

The celestial water bearer pours a streamer of faint stars across the southern sky on October nights. Aquarius is low in the southeast as the sky gets good and dark tonight, surrounding the gibbous Moon, and stands due south before midnight.

Autumn is just underway, but you can get a preview of the winter sky in the hours before dawn. Taurus, the bull, is high overhead. Orion is due south, with Sirius, the sky’s brightest star, in the south-southeast.

Epsilon Lyrae stands quite close to Vega, one of the brightest stars in summer and autumn skies, which is high in the west at nightfall. Epsilon Lyrae consists of two pairs of stars. Each pair is tightly bound, with the two pairs quite far apart.

Summer officially ended a week ago, but one of its most visible star patterns is still high overhead in the evening. The Summer Triangle consists of the bright stars Deneb, Vega, and Altair. The triangle is directly overhead about 8 p.m.

Several eagles soar across the sky tonight. The brightest is the star Vega, the swooping eagle, which is overhead at nightfall. Altair, the flying eagle, is in the southeast. The Eagle Nebula is a cloud of gas and dust that outlines a bird of prey with open wings.

The Moon is at first quarter tonight. Sunlight illuminates exactly one-half of the lunar hemisphere that faces Earth. The sunlit portion of the Moon will continue to grow until the Moon is full on October 5, the date of the Harvest Moon.

A pair of bright objects stands in the southwest this evening: the Moon and the planet Saturn. Saturn, the solar system’s second-largest planet, perches below the Moon, and looks like a bright star.

Antares, the bright heart of the scorpion, stands below the Moon as night falls, shining bright orange. The brighter planet Saturn is about the same distance to the left of the Moon.

Scutum, a small, faint “shield” of stars, scoots across the southwestern sky on early autumn nights. It represents the coat of arms on the shield of John Sobieski, a 17th-century king of Poland and one of that country’s great heroes.